So, i have made this conq+storm toon, pretty good geared (mostly focused towards damage, But got sapros and Mercurial gems and 12/8 squall upgrade for -resist)

My question is: In normal and some epic, i could (with 12/8) Frost Spikes, Freeze almost every boss, bosses like Typhon, arachne Shame, Hades etc. This was often after the squall resistance reduction debuff.

Now in legendary, i can go Battle Standard, Squall, Hit once (this should bring the Learnean Hydra FAAAAR below 0% resist) and use Frost Spikes. Nothing happens.

Now i figured it could be due to 1 of 3 reasons.
1) Bosses in legendary has alot more frost resist
2) Resistance reduction works worse on special bosses (The hydra in particular)
3) Resistance reduction doesn't affect freeze duration / effect in anyway, the bosses have just gone from around (guess 20-40 %) to (guess 70-90 %) from normal -> legendary.

Also, does resistance reduction from things like sapros and / or squall remove pierce / physical / slow resist